[HN Gopher] Computing the Eclipse
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       Computing the Eclipse
        
       Author : lawrencechen
       Score  : 41 points
       Date   : 2024-04-09 07:34 UTC (15 hours ago)
        
 (HTM) web link (writings.stephenwolfram.com)
 (TXT) w3m dump (writings.stephenwolfram.com)
        
       | cjk2 wrote:
       | This would be really cool if it wasn't a thinly disguised Wolfram
       | sales pitch.
        
       | andrewla wrote:
       | Putting aside the Wolfram Language related content, this is a
       | really interesting introduction to the mechanics of solar
       | eclipses. The notion of a "synodic" vs "draconic" really clears
       | up a lot of my questions about why there are not eclipses during
       | every new moon.
       | 
       | One thing I was wondering from looking at this is whether there
       | is a good map projection that preserves the shape of the "solar
       | disc" (my term) that represents the side of the earth illuminated
       | by the sun, weighted by the solid angle from the view of the sun,
       | so that eclipse paths would look like straight lines of constant
       | width.
        
         | dhosek wrote:
         | Such a projection would be possible-ish, but it would need a
         | different centering depending on the eclipse. The NASA solar
         | eclipse maps (these are the ones that you'll see in the
         | Wikipedia articles on the eclipses) kind of hint at in that
         | direction.
        
       | lordnacho wrote:
       | I heard somewhere that the Spanish managed to wow the people they
       | met in the new world with an eclipse.
       | 
       | Is this true? What calculations did they do to figure this out
       | with 16th century math?
        
         | rufus_foreman wrote:
         | Christopher Columbus did it to terrorize people into giving him
         | food (lunar eclipse, not solar):
         | https://en.wikipedia.org/wiki/March_1504_lunar_eclipse
        
         | herodotus wrote:
         | If they were familiar with Ptoloemy's almagest, they would be
         | able to predict eclipses using geometric methods. Not perfect
         | but surprisingly accurate according to Jayant Shah in the paper
         | "Accuracy of Ptolemy's Almagest in predicting solar eclipses"
         | 
         | More accurate methods using Newton's theories were yet to come.
        
         | antognini wrote:
         | A bit tangential, but this was one of the main ways that the
         | Jesuits were able to gain access to the Imperial Court in Ming
         | Era China. Predicting solar eclipses was one of the most
         | important functions of the royal astronomers. However from the
         | late Song Dynasty and into the Ming Dynasty there was some
         | bureaucratic decay in the Astronomical Bureau and the quality
         | of eclipse predictions declined. When the Jesuits arrived they
         | were able to make superior eclipse predictions and leveraged
         | that to gain appointments to the astronomical bureau. (And they
         | were so successful at this that the Bureau was run by a Jesuit
         | for a century and a half.)
         | 
         | Incidentally, this didn't work everywhere Europeans went. When
         | Guillaume Le Gentil arrived in southern India in the 18th
         | century he found that Tamil eclipse prediction techniques were
         | superior to the Western methods. (His own prediction was off by
         | 68 seconds whereas the Tamil prediction was off by 41 seconds.)
        
       | dhosek wrote:
       | Weird coincidence: while driving home from the eclipse yesterday,
       | at one point I was right next to the Wolfram building in
       | Champaign.
        
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       (page generated 2024-04-09 23:01 UTC)